STE V1.5 32MHz BOOSTER - STATUS

[exxos]

I've got about 6 boards working now.. Tarnishing on the CPU pins and header pins has been a problem as well. A bit of IPA and works fine. So will probably include a IPA swab so people can clean the pins before plugging the thing into the socket.

Each of the 6 boards only runs as far as loading GB6 then freezes, so I think its safe to assume none of these CPU's are going to run at 40mhz. This is a new batch I got so assume they all going to be 38MHz or 36Mhz.. the CPU;s I had before were a different source/batch which did run at 40MHz.. I've ordered some more CPU's from another place.. so will try a few of those when they come.

Currently I don't think there is a PCB problem now... I will probably run the boards though my US cleaner before trying others out.. I may even put the CPU's in the US cleaner before soldering them as well... I have wiped IPA on them a lot before soldering.. but a proper soak and clean might work better... I will probably do the same with the pins before soldering..


BTW - someone asked what german company I used it was https://aisler.net/ took me awhile to remember sorry!

Boards I had from them before I seemed to have a lot of trouble with them over the original ones I got from OSH... The current boards I got from my regular PCB guy, and granted while there are some issues, I have actually managed to fix them all so far.. So really questioning the quality of those boards in Germany , but I have not looked into it much...

I stopped using them when they messed up a order and they started taking a long time to reply (like 1 week+ for each reply!) , They had enough chances to correct this problem and I am still waiting for a reply to my last email to them. I had no offer of a refund or replacement boards, so to me they are not interested, so that is good enough for me never to use aisler again.

[PhilC]

I didn't realise the batch of CPU's that myself and RJ had were different than the current lot, so that makes sense.

[exxos]

I didn't realise the batch of CPU's that myself and RJ had were different than the current lot, so that makes sense.

Yep, "old stock" were all the test boards CPU's... I ran out of those CPUs so brought a reel from USA I think (cost a fortune!) but obviously these can't run at 40MHz

[PhilC]

Still, Mhz wise 38Mhz is 18% faster than 32 and 12.5% faster for 36Mhz, so for a computer of this age, its still an impressive boost if the application has the ability to use the extra Mhz.

Were the CPU's in the STF kit the new batch too out of interest?

[exxos]

Still, Mhz wise 38Mhz is 18% faster than 32 and 12.5% faster for 36Mhz, so for a computer of this age, its still an impressive boost if the application has the ability to use the extra Mhz.

Yeah, I wanted to push more than 32MHz over the original design.. Even so, I think effectively even if this booster ran out 32MHz, it would actually still be faster than the original booster. So 38MHz new booster is probably like be 40MHz with old booster... The new booster firmware has had a total rewrite so it is more efficient than the previous design..

Were the CPU's in the STF kit the new batch too out of interest?

Most probably yes.

I can only test them at 32MHz the original V1 booster... So I don't know how good they are until one of the new boards is totally built up and tested.

[exxos]

Had a email from Troed suggesting trying a heatsink.. Though the CPU does not actually get hot, I did documented this *somewhere* with actual temps.. But to the touch the CPU does not get warm even after long use.

So I had the idea to use freezer spray.. A quick test before and GB6 locked up after completing the first test... With the freezer spray it did 2 full loops without crashing... So definitely a improvement.

I then thought for the hell of it to up the voltage a bit to see if that would work.. Upon measuring the voltage I was actually running at 4.60V What I remember now, as I was using this SR98 PSU to power my Falcon when I was looking at the reset issues while ago and must have forgot to put the voltage back afterwards

So I put it back to 5.00V on the booster so far has done a couple of full loops... I will leave it running for a while and see what happens..

Though it is reasonable to assume at this point that 40MHz may well be back on the cards!

[troed]

I was just going to comment on that - sounded weird that they didn't get hot at all!

4.6V was probably indeed very challenging for them to be running at

[exxos]

Last time I looked was loop 14... Its locked up again Will re-seat the booster and try again...

Saying that, this motherboard has 2.2K SIL's on it, and 2.2K on the booster is a bit to low overall... Will have to take the SIL's off the MB and put connectors on the MB instead so I can swap them out.. Might have to wait until next week now though...

[exxos]

Can you guys who have this booster, try saving desktop.inf to a floppy ? it seems to be corrupting mine

I will try the machine with a stock CPU as well to make sure the machine actually hasn't got some DMA related issue....

EDIT:

No DMA issues with stock CPU... this could be issues with the pull ups being to low in value.. will swap them out on the MB and try again....


EDIT2:

Got some 10k SIL's in there now, and saving to floppy is now working fine

I'll probably move to 4.7K SIL's on future builds, then this shouldn't be a problem... Worst case really is to simply cut out the motherboard SIL's if this problem arises again, which I do not think it will.

So now I am testing again at 40MHz... See how long it runs for this time...

IMG_3425.JPG (142.3 KiB) Viewed 4113 times

[exxos]

Current test at 40MHz was 22mins (8 loops).

Will reseat the booster and try again, but I think this is just the CPU maxing out...

I will also try swapping my SR98 for my own brand power supply to see if that makes any difference...

EDIT:
10mins loop 4 the second time.. so makes sense really...

Next the exxos psu installed (was SR98 before)......nope... so its not PSU stability...

So we are back to slower clock speeds again it seems